The present disclosure relates to a semiconductor device suitable for a memory element such as an OTP (One Time Programmable) element and to a method of manufacturing the semiconductor device.
The OTP element is a nonvolatile memory element capable of storing information even when an electric power source of a device is turned off. In the past, several structures such as a fuse-type structure and an anti-fuse-type structure have been proposed for the OTP element.
In the fuse-type OTP element, a resistor is fused by flowing a large current to a resistive element formed of, for example, polysilicon or the like to change short-circuit state between both electrodes to open state therebetween, and thereby, an information writing operation is performed. However, in the fuse-type OTP element, since a large current is flown at the time of writing as described above, a transistor having a high current ability capable of flowing a large current and a wiring having a large width capable of flowing a large current therein are necessitated. Therefore, in the fuse-type OTP element, there has been a disadvantage that the whole area including a peripheral circuit is increased.
In contrast, in the anti-fuse-type OTP element, an alloy (such as silicide) formed in an electrode section is melted by applying a voltage equal to or larger than a dielectric strength voltage to, for example, an MOS (Metal Oxide Semiconductor)-type capacitive element, breaking down a dielectric film, and flowing a large current. The melted metal forms a filament between electrodes, and thereby, open state between both the electrodes is changed to short-circuit state therebetween. Thereby, an information writing operation is performed (for example, see Japanese Unexamined Patent Application Publication No. 2012-174863). In the anti-fuse-type OTP element, at the time of writing, a large current is not necessitated as much as in the fuse-type OTP element. Therefore, the anti-fuse-type OTP element is advantageous in terms of the area, and electric power consumption is allowed to be suppressed.